Handedness in Short-eared Owls

Last summer Mia and I spent four days photographing a family of Short-eared Owls in Red Rock Lakes National Wildlife Refuge.  There were two baby owls in a nest under a sagebrush guarded over constantly by the female while the male hunted and brought in food.   That food in every instance that we saw was a vole (mouse-like rodent).  Many of the photos I took were of the male in flight, returning to the area of the nest with a vole in his talons.

Male with vole

It wasn’t until I returned home and began processing the images that I began to notice that the male always seemed to carry the vole in its left foot.  This piqued my curiosity about something I’d never considered – do some birds show “handedness” – the preference of using one limb as opposed to the other?  Could this male owl, or perhaps all Short-eared Owls, be left-“handed”?

  Once again, carrying the vole in the left foot

So I decided to do an inventory of my images of these birds to see what would turn up.  After culling my photos of these owls from this trip I had 271 photos to go through.  Most of those were flight shots of the male and in more than half of them he was carrying a vole.  My goal was to try to determine how many “sorties” he made with a vole that I had photographed (I often got multiple shots of the male with the same vole in the same sortie) and determine what percentage of the time he carried the vole in each foot, right or left.  As I reviewed the photos I used the digital time stamp embedded in each image file to determine where one sortie began and another ended.

In the left foot again

It turns out that I had saved images from 13 sorties by the male where I could determine without question (in at least one of the photos in that sequence) which foot the vole was being carried in.  In some of the image sequences I couldn’t tell for sure which foot was being used so I didn’t include those in my tabulations.

And again…

The results:

• In 12 of the 13 sorties the vole was carried in the left foot
• In 1 of the 13 sorties the owl appears to be carrying the vole it its right foot early on in the sequence (though I can’t be absolutely sure) and then later photos in the same sequence show the vole in the left foot.  The bird must have transferred the vole from foot to foot in mid-flight which might still demonstrate a preference for the left foot.

These results would seem to indicate a strong preference by this male for the left foot when carrying voles in spite of the relatively low sample size of 13.  I’m very curious if this is simply a trait of this individual bird or if it’s possible that many or most Short-eared Owls are left-handed but have been able to find no other information on the subject for this species.  However, recent research does indicate that most parrot species are left-handed – the Cockatiel being the exception.

 Female carrying a vole

I did get one photo of the female carrying a vole.  Typically she would wait in the nest for the male to deliver the meal.  He would always land on a nearby perch with the vole for a short time before bringing the vole to the female and babies.  Occasionally he would wait too long and the female would become impatient and call to him in an obvious attempt to get him to speed up the delivery.  On one occasion she ran out of patience, flew out of the nest to the male, retrieved the vole and carried it back to the nest.   The photo above is of the female on that return trip to the nest.   You can see her brood patch on her belly above the vole.

And yes, she was carrying the vole in her left foot!

One out of one in the  case of the female is statistically meaningless of course but I still found it interesting and it remains that in the case of both birds collectively these owls virtually always and perhaps without exception carried the vole in their left foot.  I find that fascinating!

Ron